Механика машин, механизмов и материалов (Jun 2018)
Estimation of Technical Condition of Units of a Hydraulic Actuator of Mobile Power Means according to Volumetric Coefficient of Efficiency
Abstract
In modern mobile power tools of domestic and foreign production, the torque from the engine to the working mechanisms is transferred, as a rule, by hydrostatic drives consisting of regulated and unregulated axial-plunger hydrounits. Their technical condition directly affects the performance of machinery in general. The analysis of the operability and longevity of controlled axial-plunger hydraulic units showed that in the pre-repair operation period the share of their failures is about 20 % of the total number of machine failures. According to scientific and technical sources, the average overhaul life of the repaired controlled axial-plunger hydrounits of the 313.3 series under actual operation does not exceed 60 % of the resource of the new product. The most vulnerable hydraulic drive units are the axial-plunger motor and pump, which include precision parts and make up more than 90 % of the cost of the entire drive. If the hydraulic drive fails and the malfunction can not be repaired directly in the operating conditions, the above mentioned units are sent to specialized enterprises for repair. Usually, because of the lack of diagnostic equipment, both at the operator enterprises and at repair enterprises both units are sent for repair without preliminary diagnosis. Repair companies explain the need to send both of units for repair as they have the same residual life. The results of our studies show the absence of such a pattern. At the repair enterprises, the repair is not carried out for the same reason — the lack of diagnostic equipment. Due to this, the two units sent for repair are subjected to complete disassembly, defects identification and repair. The available research results show that in more than 40 % of cases, the units require no repair. The purpose of the work is to develop a stand and a method for assessing the technical condition of hydraulic power units for mobile power equipment, to increase the functional reliability and efficiency of maintenance, to prevent failures during operation of the hydraulic drive and to ensure the prediction of the residual life of aggregates at specified operating intervals.
